Monomeric compositions effective as wound closure devices

ABSTRACT

A biocompatible monomer composition includes: (A) at least one monomer, which forms a medically acceptable polymer; (B) at least one plasticizing agent present in the composition in an amount of from 0.5 wt. to 15 wt. % of the composition; and (C) at least one acidic stabilizing agent having a pK a  ionization constant of from about 1 to about 7. The composition can be applied to a variety of materials and is particularly suitable as in vivo tissue adhesive. A method of joining together in vivo two surfaces, e.g., body tissues, includes (a) holding damaged tissue edges together to form abutted tissue surfaces; (b) applying to the abutted tissue surfaces an excessive amount of a composition containing 1) at least one monomer, which forms a medically acceptable biodegradable polymer, 2) at least one plasticizing agent; and 3) at least one acidic stabilizing agent; and (c) maintaining the surfaces in contact until the composition polymerizes to form a thick film of polymerized composition bridging the abutted tissue surfaces.

FIELD OF THE INVENTION

[0001] This invention relates to monomer and polymer compositions usefulto form biomedical adhesives and sealants, and methods of applying them.More particularly, this invention relates to wound closure monomer andpolymer compositions and their use for medical, surgical and other invivo applications.

BACKGROUND

[0002] Products in primary use for wound closure are surgical suturesand staples. Sutures are recognized to provide adequate wound support.However, sutures cause additional trauma to the wound site (by reason ofthe need for the needle and suture to pass through tissue and the needto anesthetize the wound area via needle application) and aretime-consuming to place, and, at skin level, can cause unattractivewound closure marks. Surgical staples have been developed to speed woundapposition and provide improved cosmetic results. However, surgicalstaples also impose additional wound trauma and require the use ofancillary and often expensive devices for positioning and applying thestaples. Both sutures and staples are especially problematic inpediatric cases where the patient may have a strong fear response andrefuse to cooperate with their placement, and in geriatric cases wherethe skin tissue is weaker and prone to tearing.

[0003] Alternatively, adhesives have been proposed as wound closuredevices. One group of such adhesives is the monomeric forms ofalpha-cyanoacrylates.

[0004] Reference is made, for example, to U.S. Pat. No. 5,328,687 toLeung et al; U.S. Pat. No. 3,527,841 to Wicker et al.; U.S. Pat. No.3,722,599 to Robertson et al.; U.S. Pat. No. 3,995,641 to Kronenthal etal.; and U.S. Pat. No. 3,940,362 to Overhults, which disclosealpha-cyanoacrylates that are useful as surgical adhesives. All of theforegoing references are hereby incorporated by reference herein.

[0005] Typically, the cyanoacrylate surgical adhesive is applied to oneor both surfaces of wounds or incisions, including the internal portionsof the wound, with any excess adhesive being quickly removed from thebonding surfaces. Subsequently, the edges of the wound are held togetheruntil they adhere. See U.S. Pat. No. 3,559,652 to Coover, Jr. et al. Twocoatings of adhesive may be applied to the wound surfaces. However, thismethod of application produces significant levels of histoxicity due tothe surgical adhesive being trapped within the wound site.

[0006] An additional method of application of the cyanoacrylate surgicaladhesive to wounds or incisions involves the formation of a bridge overthe wound site. As described in U.S. Pat. No. 3,667,472 to Halpern, theincised tissues are held together and maintained in fixed relationshipuntil a cyanoacrylate adhesive has been applied over the incision andallowed the necessary time to develop a bond. Excess adhesive is removedfrom the incision. However, the composition utilized in this processsuffers from inadequate film strength and flexibility with highhistotoxicity in wound sites.

[0007] These conventional methods of application of tissue adhesivegenerally do not specify a particular method that is preferable, nor isthere any mention of placing more than minimal amounts of glue uponwounds. The conventional application techniques strive to reduceapplication of excessive amounts of tissue adhesive to the wound due tohistoxicity.

[0008] A topical tissue adhesive commercially available is Histoacryl®available from B. Braun Melsungen AG of Germany. The manufacturerrecommends use of this adhesive only for closure of minor skin woundsand not for internal use. Moreover the manufacturer recommends that theadhesive be used sparingly or in thin films because thick films do notincrease the film strength and can lead to necrosis of surroundingtissue due to thermogenic reaction. Moreover, films formed from thisadhesive are brittle, permitting severe dehiscence of wounds.

[0009] Plasticizers have been added to cyanoacrylate surgical adhesivecompositions. See, for example, U.S. Pat. No. 3,759,264 to Coover, Jr.et al., 3,667,472 to Halpern, 3,559,652 to Banitt, the subject matter ofwhich is incorporated herein by reference. However, the incorporation ofplasticizers in such compositions has led to decreased film strength ofthe polymerized material. Accordingly, such compositions have beenutilized only within the wound site and not over the wound site as abridge.

[0010] Other additives have been employed in cyanoacrylate surgicaladhesives for the purposes of modifying the cure rate and shelf life ofthe adhesives. For example, cyanoacrylate polymerization inhibitors orstabilizers including Lewis acids, such as sulfur dioxide, nitric oxide,boron trifluoride and other acidic substances, including hydroquinonemonomethyl ether, hydroquinone, nitrohydroquinone, catechol andhydroquinone monoethyl ether. See, for example, U.S. Pat. No. 3,559,652to Banitt, the subject matter of which is incorporated herein byreference. These compositions contain significant amounts of impuritiesand, thus, require substantial amounts of stabilizer to inhibitpremature polymerization of the monomer.

[0011] Other adhesives include both plasticizers and stabilizing agents.For example, U.S. Pat. No. 5,480,935 to Greff et al. describes a tissueadhesive having a plasticizer and a polymerization inhibitor. However,the plasticizers disclosed therein (i.e., alkyl phthalates) are highlytoxic and are not suitable for use in biocompatible medical adhesives.

SUMMARY OF THE INVENTION

[0012] The present invention is based on the discovery that combiningthe monomers described hereinafter with a plasticizing agent and anacidic stabilizing agent provides a surgical adhesive composition that,after application to wounds or incisions, polymerizes to form a strongand flexible bond on the wound or incision site. Furthermore, thepresent invention provides a process for application of this surgicaladhesive composition in a bridge structure that provides an unexpectedlyimproved bond strength over conventional application techniques of thepolymerized composition on the wound or incision site, which increasesthe effectiveness of such monomers and polymers in in vivo applications.

[0013] The surgical adhesive forms a flexible and strong bond overwounds and incisions. Moreover, the method of applying a surgicaladhesive to a wound or incision provides a strong and flexiblebiocompatible bond.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0014] One embodiment of the present invention provides a wound closuremonomer composition, comprising:

[0015] A) at least one monomer, which forms a medically acceptable woundclosure polymer:

[0016] B) at least one plasticizing agent; and

[0017] C) at least one acidic stabilizing agent.

[0018] In other embodiments, the present invention is directed tomethods of using the above-described monomers, copolymers and polymersmade therefrom for biomedical purposes.

[0019] In one such embodiment, the edges of a wound or incision are heldtogether and an excessive amount of the above-described surgicaladhesive composition is applied to the already pinched or abuttedopposing wound edges, preferably utilizing more than one applicationstroke. This process forms a bridge over the abutted opposing woundedges that is flexible and possesses high tensile strength. Theexcessive amount of adhesive placed on the abutted opposing wound edgesforms a thick film thereon and unexpectedly increases film strength.

[0020] For example, the present invention includes a method of forming abiocompatible film across abutted tissue surfaces, comprising; (a)holding together at least two tissue surfaces to form abutted tissuesurfaces, (b) applying across said abutted tissue surfaces an adhesivebiocompatible monomer composition, and (c) allowing said composition topolymerize and form a biocompatible film on said abutted tissue surfaceshaving an in vivo film strength of at least 70 mmHg of vacuum pressurerequired to induce wound failure, generally from 70 mmHg to 400 mmHg ofvacuum pressure required to induce wound failure, preferably from 90mmHg to 400 mmHg of vacuum pressure required to induce wound failure,and more preferably from 100 mmHg to 400 mmHg of pressure required toinduce wound failure.

[0021] Preferably, the monomer is an alpha-cyanoacrylate. The monomercompositions of this invention and polymers formed therefrom are usefulas tissue adhesives, sealants for preventing bleeding or for coveringopen wounds, and in other biomedical applications. They find uses in,for example, apposing surgically incised or traumatically laceratedtissues; setting fractured bone structures; retarding blood flow fromwounds; and aiding repair and regrowth of living tissue.

[0022] As above-mentioned, conventional surgical adhesive compositionshave included plasticizers with the adverse effect of reducing the filmstrength. It has been discovered that, contrary to prior belief, thefilm strength (e.g., toughness) under certain conditions is notadversely reduced upon the addition of greater amounts of plasticizingagent. Depending on the particular acidic stabilizing agent and thepurity of the monomer utilized in the adhesive composition, the additionof greater amounts of plasticizing agent may increase the toughness ofthe resulting bond formed on the wound. It has been discovered that weakacidic stabilizing agents do not significantly affect the polymerizationof the monomer in the present composition and provide increased filmstrength with increasing amounts of plasticizing agents.

[0023] Monomers that may be used in this invention are polymerizable,e.g. anionically polymerizable or free radical polymerizable, to formpolymers. Such monomers include those that form polymers, which may, butdo not need to, biodegrade. Reference is made, for example, to U.S. Pat.No. 5,328,687, which is hereby incorporated by reference herein. Asdefined herein, “histotoxicity” refers to adverse tissue response, suchas inflammation due to the presence of toxic materials in the tissue.

[0024] Useful 1,1-disubstituted ethylene monomers include, but are notlimited to, monomers of the formula:

CHR═CXY  (I)

[0025] wherein X and Y are each strong electron withdrawing groups, andR is H, —CH═CH₂ or, provided that X and Y are both cyano groups, a C₁-C₄alkyl group.

[0026] Examples of monomers within the scope of formula (I) includealpha-cyanoacrylates, vinylidene cyanides, C₁-C₄ alkyl homologues ofvinylidene cyanides, dialkyl methylene malonates, acylacrylonitriles,vinyl sulfinates and vinyl sulfonates of the formula CH₂═CX′Y′ whereinX′ is —SO₂R′ or —SO₃R′ and Y′ is —CN, —COOR′, —COCH₃, —SO₂R′ or —SO₃R′,and R′ is H or hydrocarbyl.

[0027] Preferred monomers of formula (I) for use in this invention arealpha-cyanoacrylates. These monomers are known in the art and have theformula

[0028] wherein R² is hydrogen and R³ is a hydrocarbyl or substitutedhydrocarbyl group; a group having the formula —R⁴—O—R⁵—O—R⁶, wherein R⁴is a 1,2-alkylene group having 2-4 carbon atoms, R⁵ is an alkylene grouphaving 2-4 carbon atoms, and R⁶ is an alkyl group having 1-6 carbonatoms; or a group having the formula

[0029] wherein R⁷ is

[0030] or —C(CH₃)₂— and R⁸ is an organic radical.

[0031] Examples of suitable hydrocarbyl and substituted hydrocarbylgroups include straight chain or branched chain alkyl groups having 1-16carbon atoms; straight chain or branched chain C₁-C₁₆ alkyl groupssubstituted with an acyloxy group, a haloalkyl group, an alkoxy group, ahalogen atom, a cyano group, or a haloalkyl group; straight chain orbranched chain alkenyl groups having 2 to 16 carbon atoms; straightchain or branched chain alkynyl groups having 2 to 12 carbon atoms;cycloalkyl groups; aralkyl groups; alkylaryl groups; and aryl groups.

[0032] The organic radical R⁸ may be substituted or unsubstituted andmay be straight chain, branched or cyclic, saturated, unsaturated oraromatic. Examples of such organic radicals include C₁-C₈ alkylradicals, C₂-C₈ alkenyl radicals, C₂-C₈ alkynyl radicals, C₃-C₁₂cycloaliphatic radicals, aryl radicals such as phenyl and substitutedphenyl and aralkyl radicals such as benzyl, methylbenzyl andphenylethyl. Other organic radicals include substituted hydrocarbonradicals, such as halo(e.g., chloro-, fluoro- and bromo-substitutedhydrocarbons) and oxy-(e.g., alkoxy substituted hydrocarbons)substituted hydrocarbon radicals. Preferred organic radicals are alkyl,alkenyl and alkynyl radicals having from 1 to about 8 carbon atoms, andhalo-substituted derivatives thereof. Particularly preferred are alkylradicals of 4 to 6 carbon atoms.

[0033] In the cyanoacrylate monomer of formula (II), R³ is preferably analkyl group having 1-10 carbon atoms or a group having the formula—AOR⁹, wherein A is a divalent straight or branched chain alkylene oroxyalkylene radical having 2-8 carbon atoms, and R⁹ is a straight orbranched alkyl radical having 1-8 carbon atoms.

[0034] Examples of groups represented by the formula —AOR⁹ include1-methoxy-2-propyl, 2-butoxy ethyl, isopropoxy ethyl, 2-methoxy ethyl,and 2-ethoxy ethyl.

[0035] The preferred alpha-cyanoacrylate monomers used in this inventionare 2-octyl cyanoacrylate, dodecyl cyanoacrylate, 2-ethylhexylcyanoacrylate, butyl cyanoacrylate, methyl cyanoacrylate, 3-methoxybutylcyanoacrylate, 2-butoxyethyl cyanoacrylate, 2-isopropoxyethylcyanoacrylate, or 1-methoxy-2-propyl cyanoacrylate.

[0036] The alpha-cyanoacrylates of formula (II) can be preparedaccording to methods known in the art. Reference is made, for example,to U.S. Pat. Nos. 2,721,858 and 3,254,111, each of which is herebyincorporated by reference herein. For example, the alpha cyanoacrylatescan be prepared by reacting an alkyl cyanoacetate with formaldehyde in anon-aqueous organic solvent and in the presence of a basic catalyst,followed by pyrolysis of the anhydrous intermediate polymer in thepresence of a polymerization inhibitor. The alpha-cyanoacrylate monomersprepared with low moisture content and essentially free of impuritiesare preferred for biomedical use.

[0037] The alpha-cyanoacrylates of formula (II) wherein R³ is a grouphaving the formula —R⁴—O—R⁵—O—R⁶ can be prepared according to the methoddisclosed in U.S. Pat. No. 4,364,876 to Kimura et al., which is herebyincorporated by reference herein. In the Kimura et al. method, thealpha-cyanoacrylates are prepared by producing a cyanoacetate byesterifying cyanoacetic acid with an alcohol or by transesterifying analkyl cyanoacetate and an alcohol; condensing the cyanoacetate andformaldehyde or para-formaldehyde in the presence of a catalyst at amolar ratio of 0.5-1.5:1, preferably 0.8-1.2:1, to obtain a condensate;depolymerizing the condensation reaction mixture either directly orafter removal of the condensation catalyst to yield crude cyanoacrylate;and distilling the crude cyanoacrylate to form a high puritycyanoacrylate.

[0038] The alpha-cyanoacrylates of formula (II) wherein R³ is a grouphaving the formula

[0039] can be prepared according to the procedure described in U.S. Pat.No. 3,995,641 to Kronenthal et al., which is hereby incorporated byreference herein. In the Kronenthal et al. method, suchalpha-cyanoacrylate monomers are prepared by reacting an alkyl ester ofan alpha-cyanoacrylic acid with a cyclic 1,3-diene to form a Diels-Alderadduct which is then subjected to alkaline hydrolysis followed byacidification to form the corresponding alpha-cyanoacrylic acid adduct.The alpha-cyanoacrylic acid. adduct is preferably esterified by an alkylbromoacetate to yield the corresponding carbalkoxymethylalpha-cyanoacrylate adduct. Alternatively, the alpha-cyanoacrylic acidadduct may be converted to the alpha-cyanoacrylyl halide adduct byreaction with thionyl chloride. The alpha-cyanoacrylyl halide adduct isthen reacted with an alkyl hydroxyacetate or a methyl substituted alkylhydroxyacetate to yield the corresponding carbalkoxymethylalpha-cyanoacrylate adduct or carbalkoxy alkyl alpha-cyanoacrylateadduct, respectively. The cyclic 1,3-diene blocking group is finallyremoved and the carbalkoxy methyl alpha-cyanoacry-late adduct or thecarbalkoxy alkyl alpha-cyanoacrylate adduct is converted into thecorresponding carbalkoxy alkyl alpha-cyanoacrylate by heating the adductin the presence of a slight deficit of maleic anhydride.

[0040] Examples of monomers of formula (II) include cyanopentadienoatesand alpha-cyanoacrylates of the formula:

[0041] wherein Z is —CH═CH₂ and R³ is as defined above. The monomers offormula (III) wherein R³ is an alkyl group of 1-10 carbon atoms, i.e.,the 2-cyanopenta-2,4-dienoic acid esters, can be prepared by reacting anappropriate 2-cyanoacetate with acrolein in the presence of a catalystsuch as zinc chloride. This method of preparing 2-cyanopenta-2,4-dienoicacid esters is disclosed, for example, in U.S. Pat. No. 3,554,990, whichis hereby incorporated by reference herein.

[0042] Preferred monomers are alkyl alpha-cyanoacrylates and morepreferably octyl alpha-cyanoacrylates, especially 2-octylalpha-cyanoacrylate. Monomers utilized in the present application shouldbe very pure and contain few impurities (e.g., surgical grade).

[0043] Component B) of the compositions of this invention is at leastone plasticizing agent that imparts flexibility to the polymerizedmonomer formed on the wound or incision. The plasticizing agentpreferably contains little or no moisture and should not significantlyaffect the polymerization of the monomer.

[0044] Examples of suitable plasticizers include acetyl tributylcitrate, dimethyl sebacate, triethyl phosphate,tri(2-ethylhexyl)phosphate, tri(p-cresyl) phosphate, glyceryltriacetate, glyceryl tributyrate, diethyl sebacate, dioctyl adipate,isopropyl myristate, butyl stearate, lauric acid, trioctyl trimellitate,dioctyl glutarate and mixtures thereof. Preferred plasticizers aretributyl citrate and acetyl tributyl citrate.

[0045] Component C) of the compositions of this invention is at leastone acidic stabilizing agent that inhibits polymerization. Suchstabilizing agents may also include mixtures of anionic stabilizingagents and radical stabilizing agents.

[0046] Examples of suitable anionic stabilizing agents include sulfurdioxide, sulfonic acid, lactone, boron trifluoride, organic acids, alkylsulfate, alkyl sulfite, 3-sulfolene, alkylsulfone, alkyl sulfoxide,mercaptan, and alkyl sulfide and mixtures thereof. Preferable anionicstabilizing agents are acidic stabilizing agents of organic acids suchas acetic acid or phosphoric acid with acetic acid being a morepreferable acidic stabilizing agent. The maximum amount of sulfurdioxide present in the adhesive composition should be less than 50 ppm,and preferably less than 30 ppm.

[0047] Examples of suitable radical stabilizing agents includehydroquinone, hydroquinone monomethyl ether, catechol, pyrogallol,benzoquinone, 2-hydroxybenzoquinone, p-methoxy phenol, t-butyl catechol,butylated hydroxy anisole, butylated hydroxy toluene, and t-butylhydroquinone.

[0048] Suitable acidic stabilizing agents include those having pK_(a)ionization constants ranging from about 0 to about 7, preferably fromabout 1 to about 6, and more preferably from about 2 to about 5.5. Forexample, suitable acidic stabilizing agents include: hydrogen sulfide(pK_(a) 7.0), carbonic acid (pK_(a) 6.4), triacetylmethane (pk_(a) 5.9),acetic acid (pK_(a) 4.8), benzoic acid (pK_(a) 4.2), 2,4-dinitrophenol(pK_(a) 4.0), formic acid (pK_(a) 3.7), nitrous acid (pK_(a) 3.3),hydrofluoric acid (pK_(a) 3.2), chloroacetic acid (pK_(a) 2.9),phosphoric acid (pK_(a) 2.2), dichloroacetic acid (pK_(a) 1.3),trichloroacetic acid (pk_(a) 0.7), 2,4,6-trinitrophenol (picric acid)(pK_(a) 0.3), trifluoroacetic acid (pk_(a) 0.2), and mixtures thereof.

[0049] When adding the above-mentioned weak acidic stabilizing agents tothe adhesive composition, it has been discovered that the addition ofplasticizing agents in amounts ranging from about 0.5 wt. % to about 16wt. %, preferably from about 3 wt. % to about 9 wt. %, and morepreferably from about 5 wt. % to about 7 wt. % provides increased filmstrength (e.g., toughness) of the polymerized monomer over polymerizedmonomers having amounts of plasticizing agents and acidic stabilizingagents outside of the above ranges.

[0050] The concentration of the acidic stabilizing agents utilized mayvary depending on the strength of the acid. For example, when usingacetic acid, a concentration of 80-200 ppm (wt/wt), preferably 90-180ppm (wt/wt), and more preferably 100-150 ppm (wt/wt) may be utilized.When using a stronger acid, such as phosphoric acid a concentrationrange of 20-80 ppm (wt/wt), preferably, 30-70 ppm (wt/wt) and morepreferably 40-60 ppm (wt/wt) may be utilized.

[0051] The compositions of this invention may also include at least onebiocompatible agent effective to reduce active formaldehydeconcentration levels produced during in vivo biodegradation of thepolymer (also referred to herein as “formaldehyde concentration reducingagents”). Preferably, this component is a formaldehyde scavengercompound. Examples of formaldehyde scavenger compounds useful in thisinvention include sulfites; bisulfites; mixtures of sulfites andbisulfites; ammonium sulfite salts; amines; amides; imides; nitriles;carbamates; alcohols; mercaptans; proteins, mixtures of amines, amides,and proteins; active methylene compounds such as cyclic ketones andcompounds having a β-dicarbonyl group; and heterocyclic ring compoundsfree of a carbonyl group and containing an NH group, with the ring madeup of nitrogen or carbon atoms, the ring being unsaturated or, whenfused to a phenyl group, being unsaturated or saturated, and the NHgroup being bonded to a carbon or a nitrogen atom, which atom isdirectly bonded by a double bond to another carbon or nitrogen atom.

[0052] Bisulfites and sulfites useful as the formaldehyde scavengercompound in this invention include alkali metal salts such as lithium,sodium and potassium salts, and ammonium salts, for example, sodiumbisulfite, potassium bisulfite, lithium bisulfite, ammonium bisulfite,sodium sulfite, potassium sulfite, lithium sulfite, ammonium sulfite,and the like.

[0053] Examples of amines useful in this invention include the aliphaticand aromatic amines such as, for example, aniline, benzidine,aminopyrimidine, toluene-diamine, triethylenediamine, diphenylamine,diaminodiphenylamine, hydrazines and hydrazide.

[0054] Suitable proteins include collagen, gelatin, casein, soybeanprotein, vegetable protein, keratin and glue. The preferred protein foruse in this invention is casein.

[0055] Suitable amides for use in this invention include urea,cyanamide, acrylamide, benzamide, and acetamide. Urea is the preferredamide.

[0056] Suitable alcohols include phenols, 1,4-butanediol, d-sorbitol,and polyvinyl alcohol.

[0057] Examples of suitable compounds having a β-dicarbonyl groupinclude malonic acid, acetylacetone, ethylacetone, acetate, malonamide,diethylmalonate or another malonic ester.

[0058] Preferred cyclic ketones for use in this invention includecyclohexanone or cyclopentanone.

[0059] Examples of suitable heterocyclic compounds for use as theformaldehyde scavenger in this invention are disclosed, for example, inU.S. Pat. No. 4,127,382 (Perry) which is hereby incorporated byreference herein. Such heterocyclic compounds include, for example,benzimidazole, 5-methyl benzimidazole, 2-methylbenzimidazole, indole,pyrrole, 1,2,4-triazole, indoline, benzotriazole, indoline, and thelike.

[0060] A preferred formaldehyde scavenger for use in this invention issodium bisulfite.

[0061] In practicing this invention, the formaldehyde concentrationreducing agent, e.g., formaldehyde scavenger compound, is added in aneffective amount to the cyanoacrylate. The “effective amount” is thatamount sufficient to reduce the amount of formaldehyde generated duringsubsequent in vivo biodegradation of the polymerized cyanoacrylate. Thisamount will depend on the type of active formaldehyde concentrationreducing agent, and can be readily determined without undueexperimentation by those skilled in the art.

[0062] The formaldehyde concentration reducing agent may be used in thisinvention in either free form or in microencapsulated form.

[0063] When microencapsulated, the formaldehyde concentration reducingagent is released from the microcapsule continuously over a period oftime during the in vivo biodegradation of the cyanoacrylate polymer.

[0064] For purposes of this invention, the microencapsulated form of theformaldehyde concentration reducing agent is preferred because thisembodiment prevents or substantially reduces polymerization of thecyanoacrylate monomer by the formaldehyde concentration reducing agent,which increases shelf-life and , facilitates handling of the monomercomposition during use.

[0065] Microencapsulation of the formaldehyde scavenger can be achieved,by many known microencapsulation techniques. For example,microencapsulation can be carried out by dissolving a coating polymer ina volatile solvent, e.g., methylene chloride, to a polymer concentrationof about 6% by weight; adding a formaldehyde scavenger compound inparticulate form to the coating polymer/solvent solution under agitationto yield a scavenger concentration of 18% by weight; slowly adding asurfactant-containing mineral oil solution to the polymer solution underrapid agitation; allowing the volatile solvent to evaporate underagitation; removing the agitator; separating the solids from the mineraloil; and washing and drying the microparticles. The size of themicroparticles will range from about 0.001 to about 1000 microns.

[0066] The coating polymer for microencapsulating the formaldehydeconcentration reducing agent should be polymers which undergo in vivobioerosion, preferably at rates similar to or greater than thecyanoacrylate polymer formed by the monomer, and should have lowinherent moisture content. Such “bioerosion” can occur as a result ofthe physical or chemical breakdown of the encapsulating material, forexample, by the encapsulating material passing from solid to solute inthe presence of body fluids, or by biodegradation of the encapsulatingmaterial by agents present in the body.

[0067] Examples of coating materials which can be used tomicroencapsulate the formaldehyde concentration reducing agent includepolyesters, such as polyglycolic acid, polylactic acid, copolymers ofpolyglycolic acid and polylactic acid, polycaprolactone,poly-β-hydroxybutyrate, copolymers of epsilon-caprolactone anddelta-valerolactone, copolymers of epsilon-caprolactone andDL-dilactide, and polyester hydrogels; polyvinylpyrrolidone; polyamides;gelatin; albumin; proteins; collagen; poly(orthoesters);poly(anhydrides); poly(alkyl-2-cyanoacrylates); poly(dihydropyrans);poly(acetals); poly(phosphazenes); poly(urethanes); poly(dioxinones);cellulose; and starches.

[0068] Examples of the surfactant which can be added to the mineral oilinclude those commercially available under the designations Tritonx-100, Tween 20 and Tween 80.

[0069] The composition of this invention may further contain one or moreadjuvant substances, such as thickening agents, medicaments, or thelike, to improve the medical utility of the monomer for particularmedical applications.

[0070] Suitable thickeners include, for example, poly-cyanoacrylates,polylactic acid, polyglycolic acid, lactic-glycolic acid copolymers,polycaprolactone, lactic acid-caprolactone copolymers,poly-3-hydroxybutyric acid, polyorthoesters, polyalkyl acrylates,copolymers of alkylacrylate and vinyl acetate, polyalkyl methacrylates,and copolymers of alkyl methacrylates and butadiene.

[0071] To improve the cohesive strength of adhesives formed from thecompositions of this invention, difunctional monomeric cross-linkingagents may be added to the monomer compositions of this invention. Suchcrosslinking agents are known. Reference is made, for example, to U.S.Pat. No. 3,940,362 to Overhults, which is hereby incorporated by,reference herein. Examples of suitable crosslinking agents include alkylbis(2-cyanoacrylates), triallyl isocyanurates, alkylene diacrylates,alkylene dimethacryl-ates, trimethylol propane triacrylate, and alkylbis(2-cyanoacrylates). A catalytic amount of an amine activated freeradical initiator is added to initiate polymerization of thecyanoacrylate monomer/crosslinking agent blend.

[0072] The compositions of this invention may further contain fibrousreinforcement and colorants, i.e., dyes and pigments. Examples ofsuitable fibrous reinforcement include PGA microfibrils, collagenmicrofibrils, cellulosic microfibrils, and olefinic microfibrils.Examples of suitable colorants include1-hydroxy-4-[4-methylphenyl-amino]-9,10 anthracenedione (D+C violet No.2); disodium salt of6-hydroxy-5-[(4-sulfophenyl)axo]-2-naphthalene-sulfonic acid (FD+CYellow No. 6);9-(o-carboxyphenyl)-6-hydroxy-2,4,5,7-tetraiodo-3H-xanthen-3-one,disodium salt, monohydrate (FD+C Red No. 3);2-(1,3-dihydro-3-oxo-5-sulfo-2H-indol-2-ylidene)-2,3-dihydro-3-oxo-1H-indole-5-sulfonicacid disodium salt (FD+C Blue No. 2); and [phtha-1-ocyaninato (2-)]copper.

[0073] The compositions of this invention can be used to join togethertwo surfaces by applying the present composition to the surface ofopposing wound surfaces that are held together. Depending on theparticular requirements of the user, the adhesive compositions of thisinvention can be applied by known means such as with a glass stirringrod, sterile brush or medicine dropper. However, in many situations apressurized aerosol dispensing package is preferred in which theadhesive composition is in solution with a compatible anhydrouspropellant.

[0074] In one embodiment, the present invention is directed to a methodof joining together in vivo two surfaces which comprises (a) holdingtogether tissue surfaces of a wound or incision to form an abuttedtissue surface; (b) applying to said abutted tissue surface acomposition of the present invention, e.g., a composition comprising 1)at least one monomer (e.g., a monomer of formula (I)) which forms amedically acceptable polymer, 2) a plasticizing agent and 3) a suitableacidic stabilizing agent; and (b) maintaining the surfaces in contactuntil said composition polymerizes.

[0075] As above-mentioned, conventional surgical adhesive compositionshave been applied in very small quantities to wound surfaces before theyare abutted, with care taken to remove excess adhesive. Thick filmsformed on wound surfaces have, in the past, resulted in increasedhistotoxicity of the wound tissues and increased film brittleness withno increased film strength.

[0076] However, the present invention is directed to a method of joiningtogether in vivo two tissue surfaces by applying to an already abuttedtissue surface of a wound or incision a composition of this invention,preferably in more than one application or coating on the abutted tissuesurfaces to provide an excess of the adhesive composition on the abuttedtissue surfaces. Any excess adhesive applied directly on the abuttedtissue surface or on the immediate vicinity of the wound or incision ispreferably not removed, although excess applied to surrounding tissuenot proximate to the wound region may be removed.

[0077] A subsequent coating may be applied immediately after applicationof a previous coating or after a previous coating has been completelypolymerized. Preferably, the monomer composition applied to the abuttedtissue surface is allowed to at least partially polymerize prior tosubsequent coatings or applications of additional monomer composition. Acoating of an adhesive composition of the present invention having amonomer different from the monomer of the first or previous coating maybe applied as the second or subsequent coating. Due to the addition ofthe plasticizing agent and the acidic stabilizing agent, the polymerformed on the abutted tissue surface possesses sufficient bond strengthand flexibility even with significant film or coating thicknesses.Suitable film thickness range from 0.1 mm to 2.0 mm or 3.0 mm or higher,preferably from 0.2 mm to 1.5 mm and more preferably from 0.4 mm to 0.8mm.

[0078] In another embodiment, the present invention is directed to amethod of joining together in vivo two tissue surfaces by application ofthe present adhesive composition utilizing various applicators. Suchapplicators include crushable swab applicators, syringes and vials withvarious dispensing nozzles or tips.

[0079] For example, the applicator tip may be detachable from theapplicator container holding the polymerizable and/or cross-linkablematerial. Such an applicator tip could be attached to the applicatorcontainer prior to use and detached from the applicator containersubsequent to use in order to prevent premature polymerization orcross-linking of the unapplied material in the applicator container. Atthis point the applicator tip may be discarded and a new applicator tipmay be attached to the applicator container for subsequent use or theapplicator tip may be reused.

[0080] Additionally, the applicator tip according to the presentinvention may comprise multiple parts, with at least one part comprisingthe initiator. For example, the component comprising the initiator maybe fabricated separately from the other component(s) of the applicatortip and assembled prior to attachment to the applicator container.

[0081] The applicator tip may also be in the form of a nozzle foratomizing liquid polymerizable and/or cross-linkable materials. Conical,flat spray or condensed stream nozzles are suitable.

[0082] The applicator tip according to the present invention may beutilized in various devices. For example, manual methods of applicationmay include utilization of hand-held devices such as syringes, adhesiveguns, pipettes, eyedroppers and the like.

[0083] The applicator tip and the applicator container may also be anintegral unit. The unit may be preformed as a single piece and chargedwith polymerizable and/or cross-linkable material. After application ofmaterial from the applicator container, the unit may be discarded.Additionally, such an integral applicator tip/applicator container unitmay be fashioned to provide the capability of recharging the unit withnew material as a multiple use device.

[0084] The applicator tip may be composed of any of a variety ofmaterials including polymerized materials such as plastics, foams,rubber, thermosets, films or membranes. Additionally, the applicator tipmay be composed of materials such as metal, glass, paper, ceramics,cardboard and the like. The applicator tip material may be porous,absorbent or adsorbent in nature to enhance and facilitate loading ofthe initiator on or within the applicator tip. For example, theapplicator tip may be composed of a material having random pores, ahoney-comb material, a material having a woven pattern, etc. The degreeof porosity will depend on the materials being used.

[0085] The applicator tip according to the present invention, where itconnects to the applicator container, may have an elongated tubularportion, out of which the mixed polymerizing and/or cross-linkingmaterial is expelled. A portion of the applicator tip which isimmediately downstream of the applicator container is advantageouslyporous in order to avoid a sharp pressure drop and ensure a constantmixed ratio profile. The structure can preferably trap any barriers ormaterials used to separate multiple components within the applicatorcontainer. Thus, any such barriers will not clog the device.

[0086] Initiators that initiate polymerization and/or cross-linking ofthe material may be applied to a surface portion or to the entiresurface of the applicator tip, including the interior and the exteriorof the tip. Alternatively, the initiator may be coated only on aninternal surface of the applicator tip. Preferably, only a portion ofthe interior of the applicator tip is coated with the initiator.

[0087] The initiator on the applicator tip may be in the form of asolid, such as a powder or a solid film, or in the form of a liquid,such as a viscous or paste-like material. The initiator may also includea variety of additives, such as surfactants or emulsifiers. Preferably,the initiator is soluble in the polymerizable and/or cross-linkablematerial, and/or comprises or is accompanied by at least one surfactantwhich, in embodiments, helps the initiator co-elute with thepolymerizable and/or cross-linkable material. In embodiments, thesurfactant may help solubilize the initiator in the polymerizable and/orcross-linkable material.

[0088] Particular initiators for particular systems may be readilyselected by one of ordinary skill in the art without undueexperimentation. Suitable initiators include, but are not limited to,detergent compositions; surfactants: e.g., nonionic surfactants such aspolysorbate 20 (e.g., Tween 20™), polysorbate 80 (e.g., Tween 80™) andpoloxamers, cationic surfactants such as benzalkonium chloride andtetrabutylammonium bromide, anionic surfactants such as sodiumtetradecyl sulfate, and amphoteric or zwitterionic surfactants such asdodecyldimethyl(3-sulfopropyl)ammonium hydroxide, inner salt; amines,imines and amides, such as imidazole, tryptamine, urea, arginine andpovidine; phosphines, phosphites and phosphonium salts, such astriphenylphosphine and triethyl phosphite; alcohols such as ethyleneglycol, methyl gallate, ascorbic acid, tannins and tannic acid;inorganic bases and salts, such as sodium bisulfite, magnesiumhydroxide, calcium sulfate and sodium silicate; sulfur compounds such asthiourea and polysulfides; polymeric cyclic ethers such as monensin,nonactin, crown ethers, calixarenes and polymeric epoxides; cyclic andacyclic carbonates, such as diethyl carbonate; phase transfer catalystssuch as Aliquat 336; organometallics such as cobalt naphthenate andmanganese acetylacetonate; and radical initiators and radicals, such asdi-t-butyl peroxide and azobisisobutyronitrile. The polymerizable and/orcross-linkable material may also contain an initiator which is inactiveuntil activated by a catalyst or accelerator (included within the scopeof the term “initiator” as used herein) in the applicator tip.Initiators activated by stimulation such as heat and/or light (e.g.,ultraviolet or visible light) are also suitable if the tip and/orapplicator is appropriately subjected to such stimulation.

[0089] The initiator may be applied to the surface of the applicator tipor may be impregnated or incorporated into the matrix or internalportions of the applicator tip. For example, the initiator may beapplied to the applicator tip by spraying, dipping, or brushing theapplicator tip with a liquid medium containing the initiator. The liquidmedium may include non-aqueous solvents, such as ether, acetone,ethanol, pentane or mixtures thereof; or may include aqueous solutions.Preferably, the liquid medium is a low boiling point solvent.

[0090] Suitable applicators for application of the adhesive of thepresent invention include those described in copending application Ser.No. 08/488,411, the subject matter of which is incorporated herein byreference. A preferable applicator is a crushable swab applicator.

[0091] Specific methods which may use an adhesive composition of thepresent invention include methods for repairing damaged living tissue toprevent the escape of fluids therethrough by holding damaged tissueedges together in an abutting relationship, applying to the abuttingtissue the monomer composition of the present invention, and allowingthe composition to polymerize; methods for stemming the flow of bloodfrom vessels which comprises holding damaged regions of the bloodvessels together, applying the present monomer composition to thedamaged regions and allowing the composition to polymerize; and methodsof bonding bone tissue to promote healing of weak or fractured boneswhich comprises holding damaged bone tissue together, applying to thedamaged tissue the present monomer composition, and allowing thecomposition to polymerize.

[0092] Repairing injured tissues (for example, to control bleeding)comprises, in general, sponging to remove superficial body fluids,holding injured tissue surfaces together in an abutting relationship andsubsequent application to the exposed abutted tissue of the presentadhesive composition. The composition polymerizes to a thin film ofpolymer while in contact with the abutted tissue surface. Tissues whichare not bleeding or otherwise covered by body fluids need not be spongedfirst. More than one coating or application of monomer composition maybe applied to the abutted tissue surface.

[0093] The monomers are readily polymerized to addition-type polymersand copolymers, which are generally optically clear (as films).

[0094] In most bonding applications using the compositions of thisinvention, polymerization of the monomers is catalyzed by small amountsof moisture on the surface of the adherents; thus desired bonding oftissues or hemostasis proceeds well in the presence of blood and otherbody fluids. The bonds formed are of adequate flexibility and strengthto withstand normal movement of tissue. In addition, bond strength ismaintained as natural wound healing proceeds.

[0095] Compositions employed in the invention are preferablysterilizable by conventional methods that include, but are not limitedto, autoclave or aseptic filtration techniques.

EXAMPLES I-VI

[0096] The compositions according to the present invention are preparedutilizing conventional mixing equipment. For example, the process may beconducted as follows:

[0097] To a surgical grade cyanoacrylate in a round-bottom flask isadded the plasticizer, the acidic stabilizer, and other formulationcomponents as described herein. The resulting mixture is mechanicallystirred until it is homogeneous.

[0098] The invention is further illustrated by the followingnon-limiting examples.

[0099] In the following examples, various amounts of plasticizer (i.e.,acetyl tributyl citrate) are utilized in adhesive compositions of thepresent invention that illustrate the effects on the strengths of thebonds formed by the adhesive.

[0100] The data presented in Table I is generated using the followingmethod:

[0101] 1. A 2″ incision is made in a 5½″×5½″ sheet of latex ({fraction(1/16)}″ thickness).

[0102] 2. An adhesive composition (i.e., 2-octyl cyanoacrylate) isapplied topically to the incision with a crushable swab with apolymerization initiated tip. The interface of the incision must not beinadvertently glued.

[0103] 3. After curing for one hour, the sheet is fixed between twosheets of plexiglass. The bottom sheet is equipped with a pressuretransducer and gas inlet. The upper sheet has a 3⅝″ hole centrallylocated in it. The test piece is positioned such that the glued side isfacing the upper sheet of plexiglass containing the 3⅝″ hole.

[0104] 4. The valve controlling gas flow is opened to pressurize thetest material. Pressure is increased until failure.

[0105] 5. Peak pressure is recorded by the transducer and recorded on achart recorder. Ten determinations per test material are made.

[0106] The results are as follows: TABLE I Concentration (w/w %) BURSTEXAMPLE of Plasticizer PRESSURE (psi) I 0.0 3.9 II 5.7 3.9 III 9.1 3.7IV 15.2 3.2 V 20.0 2.6 VI 25.9 2.1

EXAMPLES VII-X

[0107] In order to demonstrate the unexpected superiority of the in vivofilm strength provided by the adhesive composition and applicationmethod according to the present invention, various methods and materialsfor wound closure and topical administration of various surgical woundclosure devices are evaluated (Examples VII-X). In vivo strength isobjectively defined by the amount of ultimate pressure required toinduce wound failure (i.e., the amounts of vacuum pressure required toopen the wound) The biomechanical analysis is performed using theDimensional Analysis Systems (DAS), (DIMENSIONAL ANALYSIS SYSTEMS,LEONIA, N.J.). This technology is specifically designed for objective invivo biomechanical characterization of linear incision wounds. Incontrast to previous biomechanical analysis methods (e.g., uniaxialtensiometers), the DAS applies a multi-axial stress to a wound which ismore analogous to stresses experienced in clinical conditions. Moreover,the DAS does not require tissue manipulation or destructive incision ofspecimens prior to testing. Therefore, sensitive, reliable andreproducible measurements of fragile wounds may be obtained in the earlyphases of healing. The DAS further eliminates the artifact error and theexperimental variables introduced by excisional methods such as,non-viable tissue samples, inconsistent variation of sample dimensions,and flawed edges from.excising tissues.

[0108] The male Sprague Dawley rat is selected for the animal modelbecause of its genetic homogeneity, ease of handling and housing, andoverall popularity as a linear incision wound model, thus allowingcomparison of data to other similar studies. This model has been usedextensively in incisional wound research, which is well documented inthe literature.

[0109] Male Sprague Dawley rats, purchased from Harlan Sprague Dawley,Inc. (Indianapolis, Ind.) are utilized in the tests. All animals areheld seven days prior to the procedures for stabilization of diet andbehavior. Four groups of rats (Groups A-D), each with a different woundclosure method and/or surgical adhesive, are tested under identicalconditions. Each of the specimens are tested for film strength one hourafter closure of the linear incision wounds.

EXAMPLE VII

[0110] In the first group of rats, designated as Group A, a one-stroketechnique for application of tissue adhesive is employed. An adhesive ofthe present invention containing about 6% by weight of plasticizer withacetic acid as an acidic stabilizer (pK_(a)=4.8) in 2-octylalpha-cyanoacrylate is applied with a compressible ampule with a swabtip (crushable swab applicator) and is passed along the opposing woundedges in a “one-stroke” fashion for topical administration.

EXAMPLE VIII

[0111] In the second group of rats, designated as Group B, linearincisions are closed with the same adhesive using a multi-stroketechnique. The adhesive is applied with a compressible ampule passedmore than once along the opposing wound edges in a “multi-stroke”fashion, resulting in 2-3 distinct applications of adhesive.

EXAMPLE IX

[0112] In the third group of rats, designated as Group C, linearincision wounds are closed with the same adhesive using a minimalsurface exposure technique. Adhesive is applied with a UniJect™ syringe(available from Horizon, Santa Ana, Calif. USA) with approximately 3-4drops in an attempt to limit the amount of adhesive exposed to the skinsurface, thus administering the adhesive to the opposing wound edgesonly.

EXAMPLE X

[0113] In the fourth group of rats, designed as Group D, linear incisionwounds are closed with Histoacryl™ (a surgical adhesive available fromB. Braun Melsungen AG of Germany) using the application technique ofExample IX.

[0114] The results from the in vivo biomechanical analyses are displayedin Table II below. As illustrated in Table II, there are significantdifferences observed between all groups at the one hour time periodstudied. Group B, the multi-stroke technique, demonstrates a significantincrease in ultimate pressure in comparison to Groups A & C. This datasuggests that increasing the amount of adhesive applied may allow forhigher in vivo strength. Group D reveals a highly significant decreasein in vivo strength in comparison to all groups evaluated. TABLE IIReveals statistical results for direct comparisons of the alternatemethods and other techniques at 1 hour post-application. Number of InVivo strength Group Incisions (mmHg) A: one stroke 10 110.30 B:multi-stroke 10 214.57 C: minimal 10 94.36 surface exposure D:Histoacryl 10 62.80 (minimal surface exposure)

EXAMPLE XI

[0115] The efficacy of the same tissue adhesive according to the presentinvention is tested in its ability to close skin incisions in a pigmodel. The tissue adhesive, Histoacryl™, is used as a control.

[0116] Incisions are made on each side of the back of these pigs withsterile scalpel blades at a controlled depth for the incisions. Theincisions are closed either with the test material or with the control.The same adhesive of the present invention, incorporated into anapplicator, was applied onto the opposed abutted edges of the wounduntil the adhesive polymerizes (i.e., the adhesive is no longer stickyto the touch). The applicator is a transparent, flexible, plasticcylinder with an absorbent head (crushable swab). Within the cylinder isa glass vial containing the adhesive which is broken by squeezing thecylinder. As the applicator is inverted, the adhesive is squeezed out ofthe cylinder into the head and then onto the skin. Histoacryl® is alsoapplied with an applicator, which is a sealed plastic ampule with anarrow neck. The ampule is attached to a 27 gauge hypodermic needle. Theampule is inverted and the adhesive is applied by squeezing the ampuleand dripping microdrops from the end of the needle onto the opposededges of the incision. Care is taken not to touch the skin with theneedle tip. The method of applying Histoacryl® has been described by J.Quinn and J. Kissick (1994, “Tissue adhesives for laceration repairduring sporting events”, Clin. J. Sport Med., 4:245-248).

[0117] Observations are made frequently during the recovery phase,recorded approximately four hours postoperatively, and then daily todetermine if any of the incisions partially or completely separates(dehiscence), and if there are any adverse tissue responses. If a woundopens during the observation period, it is not reclosed. TABLE IIIDEHISCENCE OF PIG SKIN INCISIONS Invention ™ Histoacry ™ PIG 1 Number ofincisions 4 4 Number of partial or 0 1 complete dehiscences PIG 2 Numberof incisionc 4 4 Number of partial or 0 4 complete dehiscences PIG 3Number of incisions 4 4 Number of partial or 0 2 complete dehiscences

[0118] The pigs are observed for wound dehiscence for 10 days.Dehiscence is not observed in any incision closed with the adhesive ofthe invention. Partial or complete dehiscence is observed in 7 of the 12incisions closed with Histoacryl™. Complications such as infection ornecrosis are not observed.

What is claimed is:
 1. A method of joining together living tissuesurfaces of an incision or a laceration, comprising: (a) holdingtogether at least two tissue surfaces of an incision or laceration toform abutted tissue surfaces; (b) applying across said abutted tissuesurfaces an amount of an adhesive composition comprising at least oneα-cyanoacrylate monomer, which forms a medically acceptable polymer; and(c) maintaining said tissue surfaces in contact until said compositionpolymerizes to form a film of polymerized composition on said abuttedtissue surface, said film having a thickness of at least 0.1 mm and saidfilm having a higher film strength than a film of lesser thickness,wherein said applying is by an applicator having an applicator tip.
 2. Amethod according to claim 1, wherein said applicator tip comprises apolymerization or cross-linking initiator or accelerator for saidadhesive composition.
 3. A method according to claim 2, wherein saidinitiator or accelerator is selected from the group consisting ofdetergents, surfactants, emulsifiers, amines, imines, amides,phosphines, phosphates, phosphonium salts, alcohols, inorganic bases,thiourea, polysulfides, polymeric cyclic esters, carbonates,organometallic compounds, and phase transfer catalysts.
 4. A methodaccording to claim 3, wherein said surfactants are selected from thegroup consisting of polysorbate 80, poloxamers, benzalkonium chloride,tetrabutylammonium bromide, sodium tetradecyl sulfate, anddodecyldimethyl (3-sulfopropyl) ammonium hydroxide.
 5. A methodaccording to claim 1, wherein said applicator tip is integral with saidapplicator.
 6. A method according to claim 1, wherein said applicator isa syringe, a flexible cylinder, a tube, a pipette, or an eyedropper. 7.A method according to claim 2, wherein said α-cyanoacrylate monomer isselected from the group consisting of 2-octyl cyanoacrylate, dodecylcyanoacrylate, 2-ethylhexyl cyanoacrylate, butyl cyanoacrylate, methylcyanoacrylate, 3-methoxybutyl cyanoacrylate, 2-butoxyethylcyanoacrylate, 2-isopropoxyethyl cyanoacrylate, and 1-methoxy-2-propylcyanoacrylate.
 8. A method according to claim 1, wherein saidcomposition is sterile.
 9. A method according to claim 1, wherein saidfilm has a thickness of at least 0.2 mm.
 10. A method according to claim1, wherein said adhesive composition comprises at least one plasticizingagent present in the composition in an amount of from 0.5 wt. % to 16wt. % of the composition; and at least one acidic stabilizing agenthaving a pK_(a) ionization constant of from about 0 to about
 7. 11. Amethod according to claim 1, wherein said composition further comprisesat least one plasticizing agent in an amount ranging from 3 wt. % to 9wt. % of said composition and at least one acidic stabilizing agenthaving a pK_(a) of from about 1 to about
 5. 12. A method according toclaim 11, wherein said plasticizing agent is present in an amountranging from 4 wt. % to 7 wt. % of said composition.
 13. A methodaccording to claim 11, wherein said composition is sterile.
 14. A methodaccording to claim 1, wherein more than one application of said adhesivecomposition is provided across said abutted tissue surfaces.
 15. Amethod according to claim 14, wherein said adhesive composition appliedacross said abutted tissue surfaces is allowed to at least partiallypolymerize prior to subsequent coatings or applications of said adhesivecomposition.
 16. A method according to claim 1, wherein said adhesivecomposition polymerizes to form a bridge across said abutted tissuesurfaces.
 17. A method according to claim 1, wherein said film has athickness of 0.2 mm to 3.0 mm.
 18. A film formed across abutted tissuesurfaces made by the method of claim 1.